The BTC has already been through a mixer (as was noted by the mixer service in Klee's topic) and supposedly all records that could have traced the mixing have already been deleted (so there is no way that they can trace the hacker without at least losing their credibility as a mixing service).
I do think that the stuff about having 36 days to return the 462 BTC amount doesn't look very legit (i.e. the hacker gains 1 month to "disappear to another country").
I would speculate that it would give him time to further mix the coins and let enough time for the logs on the mixing services to be deleted. If Klee was still looking for the thief then the mixing services may wish to retain the logs and give them to klee so the thief's identity could be discovered. If klee is openly saying that he has no further claim against the thief then the mixing services would have no reason to retain logs